Exam #3: Respiratory Physiology Flashcards
What does the brain sense in controlling respiratory drive?
The respiratory centers in the medulla sense the arterial partial pressure of: - O2 - CO2 and - pH
Note that these gases must be DISSOLVED to exert partial pressure & not conjugated
What are the functions of the respiratory system?
- Gas exchange
- Acid-Base Balance
- Phonation
- Defense mechanisms (alveolar macrophages)
- Metabolism & handling of bioactive materails
What structures are included in the upper airway? What is the major function of the upper airway?
Everything from the nose to the vocal cords, including the sinuses
Conditioning of inspired air i.e.
- Warm
- Humidify
- Filter (larger than 10um)
What provides the majority of resistance in the upper airway? What happens when there is a URI?
- The nose provides 50% of the resistance to air coming into the body
- In URI, further increases in nasal resistance lead to mouth breathing when resistance is too high
Describe the branching of the airway from the trachea to the alveoli.
Trachea Main stem bronchi Segmental bronchi Bronchioles Terminal Bronchioles Respiratory Bronchioles Alevolar ducts Alveolar sacs
Where do the alveoli start to appear?
After 16th generation; the terminal bronchioles are the smallest airways without alveoli
(Respiratory bronchioles DO have alveoli)
What is considered the conuducting portion of the airway? What is the respiratory portion of the airway?
The first 16 generations of the lung, including the terminal bronchioles; this is the portion of the airway that brings gas in but does NOT function in respiration
The last 7 generations of the lung that are directly involved in gas exchange are considered the respiratory portion
Which portions of the airway contain cartilage and which do not?
Cartilage= trachea & bronchi Non-cartilage= bronchioles & alveolar ducts
What is the main source of airway resistance in the lower respiratory tract? Why?
Bronchioles
NO cartilage
When does bronchiole constriction occur? How is it treated?
Asthma, COPD
B2 agonist (albuterol)
What are the structural properties of the alveoli?
NO cartilage
NO smooth muscle
Thin membrane that is involved in gas exchange
How is mucous production & clearance balanced?
- Goblet cells & submucosal tracheobronchial glands produce mucous (PNS innervation mostly)
- Ciliated epithelial cells push mucous upward
What is the function of mucous?
Smoother air inflow
Humidifation
What is the effect of PNS stimulation in the lung?
Mucous secretion
What enviornmental factors increase mucous production?
Smoke
Pollutants
What is periciliary fluid? What is the function of perciliary fluid?
Perciliary fluid is the fluid produced by ciliated epithelial cells, which is involved in:
1) Cl- secretion
2) Na+ absorption
Describe the pathophysiology of Cystic Fibrosis.
CFTR mutations lead to:
1) Abnormal Cl- secretion
2) Inability to absorb Na+
Net= Thick mucous
What is the difference between Type 1 & 2 pneumocytes in the alveoli?
Type-1= structural “squamous lining cells”
- Fewer in number
- Account for 95% of the alveolar surface area
Type-2= surfactant producing or “granular pneumocytes”
What is surfactant? What is the function of surfactant?
Surfactant= a protein & phospholipid substance that decreases surface tension to prevent alveoli collapse
What is the respiratory unit? What is the function of the respiratory unit?
Terminal bronchiole
Alveolar ducts
Atria
Alveoli
This is the site of gas exchange
What are pores of Kohn? What is the function of the pores of Kohn?
- Pores between alveoli that provide inter-alveolar communication
- Collateral ventilation
Note that bacteria can transmit through these pores
How are capillaries associated with alveoli?
Each alveoli is wrapped around by roughly 500 capillaries–makes a “sheet of flow”
What is the respiratory membrane?
The place between the alveoli & capillary where gas exchange occurs; it includes:
- Alveolar epithelium
- Epithelial basement membrane
- Interstitial space
- Capillary basement membrane
- Capillary endothelium
What lines the alveolar surface of the respiratory membrane?
Surfactant
What pathological change in the respiratory membrane does pneumonia cause?
Increases fluid & bacteria on the alveolar side of the respiratory membrane
What is a hallmark of COPD in the respiratory membrane?
Thickened epithelial basement membrane (alveolar basement membrane)
Describe the pathophysiology of CHF at the level of the respiratory membrane.
Increased capillary hydrostatic pressure pushes fluid into the interstitial space–> increased thickness of the respiratory membrane & limits gas exchange
What can damage the capillary basement membrane? What happens with damage to the capillary basement membrane?
- Toxins
- Fluid creep into the interstitial fluid
How can autoimmune disease disrupt the respiratory membrane?
Antibody complexes on the capillary side of the respiratory membrane
Describe the composition of the lung interstitium.
Connective tissue Smooth muscle Lymphatics Capillaries Variety of other cells
*Fibroblasts
What is the function of fibroblasts in the interstitium?
Production of collagen & elastin, which provides the lung with distensibility & elastic recoil
What is the function of the plerua?
Transmitting the negative pressure produced by the chest wall that allows for expansion of the lungs
What are stomata?
Stomata are openings in the parietal pleura that serve as the exit point for pleural fluid that drains into the lymphatic system
What produces most of the plerual fluid?
Parietal pleura contains systemic capillaries that extrude fluid into the pleural space
Pathophysiology of pleural effusion.
Prevents negative pressure from allowing expansion of the lungs
When is pleural effusion most commonly seen? What is the pathophysiology?
CHF causes increased pulmonary venous hydrostatic pressure that exudes fluid from the VISCERAL side into the pleural cavity
(i.e. from the pulmonary capillaries that are directly connected to the pulmonary veins that drain into the left atrium)
In cases of hypoalbuminemia (CKD) how is pleural effusion caused?
- Hypoalbuminemia (from kidney disease)causes a decrease in oncotic pressure of the systemic capillaries (pleural side)
- This increases fluid movement OUT of the capillaries & into the pleural space
How can decreased pleural pressure (atelectasis) cause pleural effusion? What causes atelectasis?
- Block of alveoli leads to lobar collapse
- Lobar collapse decreases pleural pressure so that it is MORE NEGATIVE
- Fluid is pulled into the pleural space
E.g. Pneumonia, cancer
How is pleural effusion caused by blockage of the lymphatic system?
Stoma cannot drain
Fluid builds in the pleural space
E.g. tumor
What is the difference between Goblet cells & Submucosal tracheobronchial glands? How are these cells clinically related?
Goblet= mucous secreting cells that are increased in response to cigarette smoke
Submucosal tracheobronchial= normally present where there is cartilage & secrete mucous + serous fluid
- Increased in chronic bronchitis into the bronchioles
Compare & contrast the parietal pleura to the visceral pleura.
Parietal pleura=
- Stomata
- Microvessels closer to pleural surface, which is why most of the pleural fluid comes from the parietal pleura
- Systemic capillaries
Visceral pleura=
- No stomata
- Microvessels farther
- Pulmonary capillaries
